In production of printed wiring boards, copper surface is roughened for improving adhesion when the copper surface is coated with an etching resist, a solder resist or the like. As a method for roughening, a method of roughening the copper surface with a microetching solution containing a specific polymer compound as described in Patent Document 1 or a microetching solution containing a specific organic acid as described in Patent Document 2 is conventionally known. According to the above-mentioned roughening method, adhesion to a solder resist and the like can be improved because deep irregularities are formed on the copper surface.